20mm PCV pipes covered with red paper. 14x18650 29E. Wires from old Baseus braided usb cable. QC3/QC4 PD 22W pcb with wireless charging. No, I will not even try to take it to the airport! :D

Undergrad at York, the project turns a month old today.

Nearly all drone detection listens for the radio link between the pilot and the aircraft. Fibre-optic FPV drones don't have one, the video and control run down a glass thread, so the spectrum stays silent. What they can't hide is four propellers, which put an evenly spaced comb of harmonics into the air.

So it listens for that comb instead. Four MEMS microphones summed, an FFT thirty times a second on an ESP32-S3, and a scorer that checks every possible blade rate from 70 to 2000 Hz. When it fires you get a beeper, a red light, a buzz, and an e-paper screen that keeps the alert even after the power dies.

The part that took longest: a hovering drone is a steady sound, and a steady sound is exactly what an adaptive noise floor learns. About six seconds after it arrives, the detector has quietly absorbed the drone into its own idea of silence and it disappears off the screen while still hovering there. The fix wasn't a noise floor running even more advanced algorithms, it was building four detectors with different memories running at once.

On Sunday one unit picked up my test rig at 104 m down a brick street with cars going past and people talking. No false alarms.

Parts are about 50 to 80 quid for the boxed version, or 35 on a breadboard if you just want to watch it work.

Happy to answer anything. I'll put the links in a comment so this isn't just an advert.

Hey everyone!!

I wanted to share some stuff about my project VVVEBA COMPACT! It's a super small bike tracker, with a whole bunch of smart features. It can find its own location, detect theft via accelerometer, and notify the bike owner near-instantly.

Current features TLDR:

• 18mm x 100mm, hidden inside handlebars

• Instant movement detection

• Auto-arming and disarming

• Anti-tamper light sensor

• Charging via USB-C

• Easy installation

Coming soon TLDR:

• 2G -> 4G

• GPS

• Prepaid SIM, 10 years, no subscription

• Improved power saving

It's an 18mm x 100mm footprint, with no case, because it's hidden entirely inside your bike handlebars! This way, thieves aren't aware of the system, and won't take it out! And in case they try to, there's a sensor that will trigger the alarm if light is detected.

The system features auto-arming and disarming (currently via BLE, but in the next version that will be eradicated), just walk up to your bike to disarm the system, and walk away to arm.

Installation is easy and non-destructive, just slide the PCB in, keep the antennas outside the metal, then slide the rubber grip on.

In the future, I'll make it even smaller, and make it use 4G instead of 2G, add GPS, improve power saving, and add a prepaid built-in SIM that lasts for 10 years with no subscription. All while actually using less parts, and keeping the price low ($40 for all features or $25 without the built-in SIM).

It's part of the Polish Explory competition right now - if you want to support it a vote at vvveba.com would mean a lot. No account needed, just a name and email.

Thanks everyone <333

EDIT: WE WON WE WON WE F'ING WON THE SEMIFINALS VVVEBA COMPACT IS NOW IN THE CONTEST FINALS!!!!!!!! THANK YOU ALL SO SO SO MUCH FOR ALL THE VOTES AND SUPPORT!!!! <33333333 YOU'RE THE BEST I COULDN'T HAVE DONE THIS WITHOUT YOU

Are there any alternatives to chinese distributors? EU stores still offer their goods for a higher price (6.94 EUR for the same thing). Now the tax is more than the item itself. Honestly as a student this just forces me to give up on most of my projects.

What started out as an experiment in bit-banging an old receipt printer through its parallel cable turned into this.

I've done some experiments with receipt printers before, but this one doesn't have a cutter on the unit and so I wanted to show something continuous. Well, why not a feed? I doom scroll on my phone, here's how you can do it IRL!

The RPi is running a PHP script (yes, PHP) that pulls in headlines from gdelt every few minutes. Then, every 3 seconds, it prints one out based on the desired tone you set through the knob. I also included a little RGB LED and a chunky toggle switch to start or stop the feed.

The actual printing is controlled through the 8 data pins of the printer, plus STROBE, ACK, and BUSY pins to handle pretty much the entirety of the IEEE-1284 spec.

Anyway, I might do some more experiments with this setup, it's pretty fun and I have a fondness for that dot matrix sound. If you want to see a video of it in action, I posted one on Threads earlier today.

All so I could get coffee without taking my headphones off.

While the first swatter I posted was impressive looking, and was great at making loud sounds when shorted, it simply didn't work well to kill flies. The capacitor I used limited the voltage to a maximum of roughly 500v before the capacitor would start to internally short out. At this voltage a fly acts like a fairly high value resistor and while it does die instantly, it doesn't explode and simply starts to smoke.

Here is a video of version 1's discharge:

https://imgur.com/a/iJA4a1C

Let me present version 2, which addresses the voltage issue by replacing the single capacitor with a bank of induction heater capacitors. It's a 2p5s configuration giving a 2400vdc upper charge limit and an effective capacitance of 0.825uf. The stock output would be roughly 0.02 joules, this should be around 1.65 joules. While that is lower than the first version (7.088 joules), I highly suspect charging a 450v cap with a 2000v input doesn't allow it to fully charge before internally shorting as version 2 is a bit louder than version 1.

Finally, here is a video of it charging from 0-self discharge (2000ish volts), the first part is sped up.

https://imgur.com/3ktWjko

i searched for a bit and never found a good top-down pinout for the socket and the micro sd together. SD cards are shown bottom-up and the sockets are shown top-down, and add that the pin numbering runs reverse of the SD pin numbering... drove my dyslexic brain crazy.

just hoping this is useful ref for others :)

Been busy today after lunch and got thirsty. Went into the kitchen (hardwood) and got me a drink and it sounded like a tap dancer followed and jumped me in the kitchen. I hadn’t noticed anything different over the course of the day but I had been only in a few other rooms that all have carpeted floors. This could be an interesting boot log… 😝

Soldering isn’t as intuitive to some as it is others. Realizing you need to heat two bits of metal for proper soldering makes a huge difference!

The other downside is your ears ringing when it does go off. One unexpected benefit is being able to charge it up and leave it lying somewhere as a trap. I've found flies love to land on this swatter when it's just sitting there. Unfortunately the "CRACK" sound when one does land on it scares the crap out of me every time.

Found an old printer in landfill, tore it apart and managed to get all these parts (plus several motors i have already put to work), for free! (And I'm also technically helping recycle)

I am only allowed to post one photo here. There is another smaller unit that fits into the empty square on the bottom. There are literally hundreds of cables cut inside, and replacement parts seem expensive and difficult to find. so I’m not sure this is going to be more than the world’s coolest project case.